ITTO20110762A1 - SYSTEM OF GENERATION AND USE (FOR ACCUMULATION AND DELIVERY) OF ELECTRICITY PRODUCED BY POWER SOURCES OF POWER CURRENT CONTINUES, AND ITS RELATED SYSTEM MANAGEMENT METHOD - Google Patents

Description

DESCRIPTION of the Industrial Invention having the title: -â € œSystem for the generation and use (for accumulation and supply) of electricity produced by modular direct current electricity sources, and relative method of managing the systemâ €

DESCRIPTION

FIELD OF APPLICATION OF THE INVENTION

The scope of application of the invention concerns a system for the generation, management and use of electricity produced by modular direct current electricity sources, and the related system management method.

STATE OF THE TECHNIQUE

A significant part of the electricity production systems is still today made up of large plants, for which the problems concerning the transport and distribution of energy are relevant, in the sense that it is essentially important to minimize the losses along the lines, which are crossed by monodirectional and fairly regular currents. The transport of energy takes place in high voltage along most of the path taken.

In the future, on the other hand, an increasingly significant portion of electricity will be produced in small quantities and therefore will necessarily be fed into the grid at medium or low voltage; it will therefore be very important to minimize the transformations and transport of the energy produced. The ideal condition foresees that there are â € œenergy islandsâ €, territorially compact, in which the production and consumption of energy are roughly equivalent and in which the energy exchanges between islands, and in particular between non-adjacent islands, are as much as possible. reduced.

Therefore, there will be significant quantities of energy produced in small quantities, both due to the fact that small plants will be widespread, and because even the largest plants will be able to produce little energy.

In the following, reference will be made by way of example to electricity produced by photovoltaic conversion systems. In fact, the photovoltaic energy source very effectively exemplifies the problems that will arise with the spread of Renewable Energy Sources (hereinafter also referred to as FER) and the â € œislandâ € network infrastructures. However, similar problems could be posed in relation to other energy sources that lend themselves to distributed diffusion having operating characteristics similar to photovoltaic plants, such as plants for the production of energy from renewable sources based on the photoelectrochemical conversion of solar energy.

Or even more generally to modular direct current electrical energy sources, such as for example micro-wind with direct current dynamo (DC), or systems for transforming mechanical energy into direct current electrical energy, etc ...

Consequently, many of the conclusions that will be reached will be generalizable and not limited to the case of the presence of electricity produced with photovoltaic systems, but also to these other types of systems, in which non-programmable energy sources are involved, for which it is not It is possible to program a production profile over time, including in the profile, not only the power, but also the current-voltage characteristic.

As is known, solar radiation affects the whole territory, and therefore the exploitation of this radiation to produce electricity is naturally distributed throughout the territory. Furthermore, since the conversion efficiency is not particularly high, an area of considerable size is generally required to produce a significant amount of energy. It is therefore foreseeable that in the future these photovoltaic systems will be distributed over vast territories, as, for example, buildings with roofs suitable for hosting the installation of such systems are distributed.

Even if the weather forecast will improve further, and therefore it will be easier and easier to predict whether a day will be more or less sunny, it will never be realistically possible to have a forecast of the instantaneous production profile of a photovoltaic system, which is characterized, on days when there are some clouds in the sky, from enormous variations (even from maximum production to very low or no production) in a few seconds, for example in correspondence with shading due to the rapid passage of clouds. Furthermore, even when an instantaneous production profile is predictable, it is not conceivable to expect a consumption profile capable of following the rapid changes in production that are typical of a photovoltaic system.

It is therefore clear how the problem of grid balancing is destined to become an increasingly important problem as the share of energy that will generally be produced from non-programmable sources (which are the sources that exploit spontaneous and non-programmable or forced natural phenomena , such as photovoltaics). The concept of grid balancing is an instantaneous concept, i.e. the grid must be balanced moment by moment, and imbalances of the opposite sign, even in rapid sequence, are not compensated for but are added up in terms of negative effects on the integrity of the electricity system .

It is known to try to solve the balancing problem by resorting to Energy Storage Systems (hereinafter also indicated with the acronym SAE). These systems are able to absorb and store energy when it is produced, and to make it available to loads when they require it.

Currently, a renewable energy production plant based on known photovoltaic energy is composed of a certain number of solar panels connected to an inverter system that converts the energy, intrinsically produced in the form of direct voltage by the panels, in alternating voltage so that it can be used by local users or sold, again in alternating form, to the public energy distribution network.

The inverter system then receives the energy generated in direct current and converts it into alternating by adapting the load seen from the source to the power conditions, in terms of voltage-current pair (I-V), generated by the panels instant by instant. This typically occurs with control systems, for example based on processing carried out according to MPPT (Maximum Power Point Tracking) algorithms. This solution has some drawbacks:

- the direct-alternating conversion generates conversion losses;

- for certain ranges of current and voltage values, the inverter cannot operate or operates with low efficiency so that the energy generated by the RES is lost in whole or in part;

- in some particular conditions or times, the grid may not be able to absorb the energy generated by the plant and therefore it is forced to interrupt the flow with consequent loss.

The latter occurrence typically occurs in poor or insufficient lighting conditions (sunrise, sunset, fog, mist or cloudy sky).

This typical configuration, in which all the energy produced is directly converted into alternating mode, is inefficient when the loads are in continuous mode, as a double conversion becomes necessary to bring it back to continuous mode.

However, this inefficiency has so far been of little significance as the typical loads are in alternating regime and most of the production is fed into the grid. This is bound to change in the near future, as grids will not be able to absorb increasing amounts of energy produced in an unscheduled way without suffering from imbalance problems.

Consequently, SAE energy storage systems must be inserted downstream of the production systems, and these, in the charging phase, are comparable to continuous loads.

However, even in the typical configurations between photovoltaic system-inverter, where all the burden of adapting between RES and inverter is exerted by the inverter, when the energy production falls below a certain threshold, the Direct current electricity cannot be converted to alternating current and is therefore lost.

According to the known art, an attempt is made to introduce flexibility by introducing flexible configuration techniques. In these cases, however, since the solar panel system is typically organized in strings, when some panels are occasionally shaded, and therefore their production can drastically decrease compared to other unshaded panels, these panels are excluded from production, but normally this exclusion involves the whole string in which these panels are inserted: this measure therefore involves a waste of energy, as other panels of the excluded string would continue to produce energy effectively.

A method described in the article â € œAn Adaptive Photovoltaic-Inverter Topology â € “Mahamoud A. Alahmad et al., University of Nebraska (USA), 2011-IEEE 978-1- is known to overcome this kind of losses. 61284-220-2 / 11â €. In this article it is proposed to use several inverters with different characteristics that are connected in a programmable way to strings of solar panels in order to expand the range of lighting values for which the system continues to produce energy compared to a photovoltaic system configured in fixed way, as it normally happens. In order to optimize the coupling between the photovoltaic system and the inverter, the length of the strings, which determines the output voltage of the system, is configured in a flexible way, in order to create longer strings when production is It is smaller, and shorter strings when the output is greater. According to this known method, the realization of flexible series-parallel circuits normally makes use of switch arrays, as shown in Fig. 1, which represents a typical case in which the photovoltaic modules can be connected to a switching matrix that allows you to modify the various connections.

However, this method of connection based on a switch matrix has the disadvantage of requiring a lot of wiring as the individual photovoltaic modules must be equipped with cables that cover the distance between themselves and the switching matrix. It is clear that in the case of rather extensive photovoltaic systems such wiring becomes quite expensive, also in terms of cost (it is noted that even the switch arrays are quite complex systems as the size of the array increases). Furthermore, in the solution proposed in the article cited, more inverters are required, and therefore the losses introduced during the conversion of energy from direct to alternating continue to exist.

In any case, this solution does not solve the problem of compensating for the very rapid imbalances caused by the lighting conditions of the panels, which can cause sudden changes in the supply of electricity at the exit of the system.

The configuration of a modular system for the generation of direct current energy currently widely used, requires that the individual modules (panels) are connected in fixed strings. Each string consists of a fixed number of modules connected in series, and these strings are then connected in parallel. The output of this series-parallel combination is connected to an inverter which transforms the incoming energy bringing it to an alternating regime that can be fed into the grid or used by common loads operating in alternating regime. It is clear that neither the power nor the current-voltage characteristics of the production plant are constant and vary from zero to the peak values of the plant. It is for this reason that the inverter technology has evolved to be able to present in the input stages all the necessary adaptation mechanisms that serve to make the inverter stages work at the best of efficiency. It is also clear that, in any case, the performances of these inverters are optimal in a certain range of input values, while their performance is lower when departing from this range. According to the most common and frequent configurations and as already mentioned, if it is also planned to use the energy storage performance through SAE, generally the energy is supplied in alternating regime to the SAEs by interposing the rectification systems called battery chargers ( generally quite expensive), also characterized by an efficiency lower than 100%.

From what has been said it is clear that every known type FER-SAE system presents adaptation and management problems that are normally faced by resorting to a certain number of DC-AC and AC-DC transformations and adaptations which then allow each apparatus to operate at optimal, even in the presence of a very variable starting energy source. However, it is evident that every adaptation and transformation subsystem introduces losses and reaches non-ideal operating points.

A theoretical alternative to the use of AC / DC battery chargers to proceed with optimal continuous coupling with storage systems would consist in the use of DC / DC converters. However, this solution would introduce excessive costs that would be necessary to equip each single module with a converter of adequate quality and capable of working on a sufficiently wide range of values. However, it should be emphasized that even these converter apparatuses do not have totally free tolerances of input values.

A further problem area is constituted by the fact that the evolution of the electrical systems of the future seems to proceed towards systems that are defined as â € œSmart Gridâ €, that is electrical networks that will no longer be â € œsimpleâ € transport infrastructures, but they will also incorporate energy management functions interacting automatically with loads, with production sources and with SAE.

This concept of â € œSmart Gridâ € combined with the fact that many RES are distributed energy sources of medium-small size, determines, as already stated, a push towards the diffusion of â € œislandâ € or â € œenergy districtsâ €. These â € œenergy districtsâ € are characterized by the use of computers, also known as controllers, responsible for managing the energy resource in all its aspects. The number of these computers, their physical location and the details of the functions assigned to them, are still the subject of various proposals, and it is not excluded that the real development of the concepts of `` Smart Grid '' will be based on architectural schemes that differ from zone to zone and from operator to operator, without affecting the potential effectiveness of the â € œSmart Gridâ € in terms of efficient energy management. A known example of a controller that implements a procedure to optimize the energy efficiency of an electrical system that includes loads (more or less flexible), energy sources (RES) and SAEs is described in US-7783390- B2. However, the electrical system described provides for the positioning of the SAEs downstream of the inverters, with the onset of the problems already described above, relating to the presence of AC / DC converters for powering the SAEs.

SUMMARY OF THE INVENTION

Therefore, the purpose of the present invention is to indicate a system for the generation and use (by accumulation and supply) of electricity produced by modular direct current sources of electricity, and the related system management method, suitable for solving problems on exposed.

The object of the present invention is a system for the generation and use (for accumulation and supply) of electrical energy produced by modular direct current electrical energy sources, comprising: a system of interconnected modules for the production of direct current electrical energy, said system of interconnected modules being positioned upstream of one or more DC / AC conversion systems; a system of interconnected elements for the accumulation and supply of electricity produced by said modules (panels) for producing electricity, said system of interconnected elements being positioned upstream of said one or more DC / AC conversion systems; at least one electronic control unit, configured to manage the interconnections between said modules and the interconnections between said elements in such a way that at least some of said interconnected modules supply electricity directly to at least some of said elements for storage and delivery, and / or to said one or more DC / AC conversion systems, and that at least some of said elements deliver electricity directly to said one or more DC / AC conversion systems.

Preferably in said system of generation and use (for accumulation and supply) of electrical energy, said at least one electronic control unit is also configured in such a way that said system of interconnected elements delivers electrical energy directly to a DC load system .

Preferably in said system of generation and use (for accumulation and supply) of electric energy, said system of interconnected modules (panels) for the production of electric energy comprises two or more first strings, each first string comprising one of said first electric lines, said at least one electronic control unit comprising means for determining parallel connections between said first strings, or for splitting groups of first strings in parallel.

Preferably in said system of generation and use (for accumulation and supply) of electric energy, said system of interconnected elements for the accumulation and supply of electric energy comprises two or more second strings, each second string comprising one of said second electric lines , said at least one electronic control unit comprising means for determining parallel connections between said second strings, or for splitting groups of second strings in parallel.

A particular object of the present invention is a system for the generation and use (for accumulation and supply) of electricity produced by modular direct current electricity sources, and the relative method of managing the system as better described in the claims, which form part integral to this description.

BRIEF DESCRIPTION OF THE FIGURES

Further objects and advantages of the present invention will become clearer from the following description of preferred embodiments thereof, described purely by way of non-limiting example, with reference to the attached drawings, in which:

Figure 1 shows an example of an interconnection system between photovoltaic panels of a known type;

Figures 2 to 5 show examples of embodiment of an interconnection system between photovoltaic panels in accordance with the present invention;

Figures 6 and 7 show interconnection block diagrams between a renewable electricity generation system, an electrical energy storage system, and a related control system in accordance with the present invention;

figure 8 shows an example of realization of an interconnection system between cells of the electrical energy storage system object of the invention;

Figure 9 shows an example of an operational flow diagram of the control system object of the invention. The same reference numbers and letters in the figures identify the same elements or components.

DETAILED DESCRIPTION OF EXAMPLES OF IMPLEMENTATION

In the following, specific reference will be made to a non-limiting case of electricity produced by photovoltaic conversion systems. However, the scope of application of the invention is intended to be extended in any case to plants for the production of energy from renewable sources based on the photo-electrochemical conversion of solar energy. The scope of application of the invention is extended in an even more general sense to modular direct current electrical energy sources, such as for example micro-wind with direct current dynamo (DC), or mechanical energy transformation systems in direct current electricity, etc ...

According to a first aspect of the invention, it exploits the fact that RES plants, and in particular those made up of photovoltaic plants, are characterized by generally being composed of panels or modules that are quite small compared to the size of the overall plant.

These modules can be connected together in such a way that they can be combined in series and / or in parallel with absolute flexibility. Figure 2 illustrates how this flexibility can be achieved through the very simple actuation of a number of switches.

Figure 2 shows how the single modules M1, â € ¦ .. Mn of a hypothetical circuit can be organized into strings of variable length by the operation of simple switches I1, â € ¦.In We mean by â € œstringâ € a set of modules connected so that they can be presented outside, all together, with just two terminals. So let's imagine the modules ordered in a row, even if it is clear that in practice this row can be compacted in a kind of serpentine in order to rationally occupy the available space.

According to the instantaneous behavior of each module, it is possible to establish the number of consecutive modules to be connected in series, thus determining the desired voltage, which is of the continuous type, across the circuit, identified as Anode A1 (positive terminal) and Cathode C1 (negative terminal). Once the desired number of consecutive modules to be connected in series has been reached, the series connection is interrupted and, by suitably operating the switch as shown in figure 2, it is possible to bring the electrodes of two consecutive panels respectively to the anode A1 and to the cathode C1 of the system, to then begin to build a new series (or string) of modules. All the various series (or strings) thus constituted are therefore connected in parallel with each other.

Figure 2 shows in its upper and lower parts only one Anode and one Cathode. However, it is possible to envisage a system with 2, 3 or a generic number â € œNâ € of Anode-Cathode pairs, organized in such a way that the entire set of modules can be partitioned into 2, 3 or â € œNâ € different sub-circuits or sections.

Figures 3.1 and 3.2 below show examples of circuits that can be divided into 2 or 3 divisions.

The case of dividing the energy produced into two sections S1 and S2, Fig. 3.1, is particularly simple. Sets of strings of modules connected in parallel form a section, S1 or S2. Here it is sufficient to place the two input / output terminals of each section at opposite ends of the Anode and Cathode and open the switches appropriately to separate the strings according to the desired proportion.

Even the division into three sections Sâ € ™ 1, Sâ € ™ 2, Sâ € ™ 3 (Fig. 3.2) is very simply feasible by opening the Cathode and Anode conductors of the sections in two points instead of just one as in the case of splitting in two. In this case, another input / output terminal will be connected to a new pair of conductors.

From the examples given it is clear how it is possible to generalize the number of divisions, by appropriately organizing the connections of the strings.

The division into several sections of strings can be used, for example, to supply the electricity produced by the various sections to different users.

The wiring diagram shown in Fig. 2 provides for the use of switches positioned between the modules, the wiring is considerably reduced compared to the case of the known art in which the switches are concentrated in a matrix, but the installation of the system with the creation of the relative connections can be further simplified.

In fact, to create the diagram shown in Fig. 2, it is possible to proceed in an extremely simple way by positioning the switches in correspondence with the electrodes of each photovoltaic module or panel, thus integrating them into the panel itself.

As shown in Fig. 4, it is sufficient that each single module N-1, N, N + 1, includes a pair of simple two-position switches I41, I42, and that it has three input terminals MI and three output terminals MU (in the figure those of module N are identified). This feature is particularly advantageous in the installation of large photovoltaic systems, which occupy very large areas and for which the simplicity of installation and maintenance is a relevant factor, and therefore the possibility that the necessary switches are integrated into the module itself (without the need for to install them separately) It is undoubtedly interesting.

It is therefore sufficient to lay the photovoltaic system by connecting the three output terminals of each panel with the three input terminals of the next panel with a three-wire cable.

The three wires represent respectively the â € œanode lineâ € A4, the â € œcathode lineâ € C4, and the â € œstring lineâ € S4. The â € œstring lineâ € S4 is used to connect the anode of a panel with the cathode of the adjacent panel if the two panels are to be connected in series. The panels can also be connected all in parallel, closing the anode of each panel on the anode line A4 and the cathode of each panel on the cathode line C4. The typical case, however, provides that series circuits are connected together in parallel. It is clear that the circuits to be connected in parallel (which in the case in question behave as generators) must all have their point of maximum efficiency at the same voltage, in order to limit the occurrence of unwanted currents. Normally, therefore, when it comes to connecting modules that are all identical to each other, it will be necessary to configure series circuits consisting of an equal number of modules, to then connect all these series circuits, to each other, in parallel.

It is obviously possible the case of modules that are different from each other, for example illuminated in a heterogeneous way, such as solar panels which for aesthetic reasons are mounted with different inclinations to follow the surface of a building, or even with a different type of use of energy source,. Their mutual connection, for example in parallel, will be more complex, but still possible, having to search for configurations in which all the circuits connected in parallel have an optimal (or in any case acceptable) working point at the same voltage.

Therefore the cathode of each panel must be connected either with the anode of the adjacent panel through the `` string line '' S4, if to be connected in series, or with the `` cathode line '' S4 if this panel constitutes the negative end of the string; while the anode of each panel must be connected either with the cathode of the adjacent panel, if to be connected in series, or with the â € œanode lineâ € A4 if this panel constitutes the positive end of the string.

As shown in Figure 5, by slightly complicating the contact system, and by adding a switch, it is also possible to exclude a single panel.

The anode I51 and cathode I53 switches of a panel can also be placed in a third position (in addition to those provided on the basis of what is described in relation to fig. 4) in which they do not make contact with any line: in this case the S5 string line must be closed with a special switch I52. Thus, by positioning the switches, a panel is excluded.

The known methods with which a panel is excluded (when for example shaded and / or damaged), would not allow to restore the optimal string length, and therefore, such situations are managed in the known art by excluding a € ™ entire string.

The control of the switches can be remotely controlled and managed by a control system at the level of the â € œenergy districtâ € to which the plant is located. The activation of the switches can be simply carried out with an electric command carried on the same transfer line as the electricity (for example on the anode and cathode lines) with `` Conveyed Wave '' (Power-Lines) techniques of per sà © notes. Note that the command to be sent to each switch is, in the simplest case, one bit.

Compared to traditional â € œPower Lineâ € applications in which data is transferred on cables in which there is an alternating energy transmission, this case appears simpler as the energy transmission rate is continuous, and therefore it is very easily separable from any carrier, even at a relatively low frequency on which to transmit the data. In any case, one of the many standards already defined for this kind of application can certainly be used for this purpose. As an example, the IEEE P1901 standards are mentioned, or those defined by industrial alliances such as the â € œUniversal Powerline Associationâ € or the â € œHomePlug Powerline Allianceâ €.

Even if the transmission needs of this application are extremely reduced, and therefore there are certainly no problems in using the “Conveying Waves” technique, it is possible to use an additional device aimed at further reducing the disturbances. Since the activation of the switches is not an operation to be carried out continuously and at high frequencies, it is possible to transmit all the commands to all the switches, without them switching immediately after receiving the command, and then switching with a fixed delay, or upon receipt of a â € œtriggerâ € signal. In this way it is avoided that, due to the commutation of the first switches, disturbance transients are generated which could hinder the transmission of the commands for the last switches.

Given the simplicity of the solution, it is possible to integrate these switches into the structure of the panel itself during construction, with marginal additional costs. In this way it is possible to produce panels that can be connected very simply and configurable in a very flexible way in series-parallel combinations.

In this case the `` cathode line '' and `` the anode line '' pass through the `` Connection system '' of each module, and are therefore also easily interruptible and therefore suitable for creating the system partitions described above. .

It is clear that for partitions higher than order two, it is necessary to pass further pairs of anode / cathode lines as explained previously. It is therefore clear that, if the anode and cathode lines are to be integrated into the structure of the modules (for example to avoid the laying of external wiring), these lines (although they can always be integrated into the structure) must be two-row in the if you want to allow three-partitions, creating the wiring diagram shown in figure 3.2. More partition orders will require the anode and cathode lines to be made with increasing numbers of conductor lines). Variants that aim at further savings in wiring are possible by positioning the triplets of input and output terminals in an appropriate way (for example on opposite sides of the panel). It is also possible to foresee the presence in the panel of complementary interlocking plugs or sockets which do not need any external wiring and which also serve to strengthen the mechanical coupling between the panels of the photovoltaic grid.

The switches can also be configured in such a way as to make it possible to remove the panel, in case of breakdown, repair, replacement, for example. For example, it is possible to equip the panel with input and output connectors, which connect the cathode, anode and string lines to the switches. In the case of integration of the switches in the panel, the connectors include connections such that, in case of removal of the panel, they short-circuit the string line and open the connections to the anode and cathode lines. Or in the case of switches outside the panel, it is sufficient to operate the switches as described above, and disconnect the panel connectors.

The realization of said circuit variants is within the reach of the person skilled in the art.

In general it can be said that, given a set of photovoltaic panels, it is possible to organize them by connecting them flexibly in order to have a predetermined number of outputs on which to divide the generated or absorbed power by controlling current and voltage, since this control can be carried out with precision. given by the current and voltage characteristics of the individual generating elements.

We have also seen how, by applying the flexible configuration techniques of the strings mentioned above, it is possible that even a classic RES, such as a photovoltaic system, can be configured in such a way as to present a controllable voltage at the output, depending on the accuracy of the voltage. output from the working voltage of the single panel in certain temperature and irradiation conditions, also contributing to optimally solving the above-mentioned energy balancing problems.

According to further aspects of the present invention, similarly to what can be done in flexibly reconfiguring the parallel series connections of a modular direct current electricity generation plant, it is also possible to reconfigure the connections of an SAE storage system. In fact, most of the storage systems are characterized by being composed of elementary modules which, in general, are connected in a fixed way to have a roughly constant voltage at the terminals and to be able to deliver the declared power. However, in the downstream application of a photovoltaic system, even an SAE can be conveniently made in such a way as to have a configuration of its internal connections that is flexible and such as to accept different charging voltages and currents.

Therefore by modifying the parallel series connections of both RES and SAE, and being able to partition both RES and SAE, it is possible to obtain optimizations in energy management.

The invention teaches how to operate such configurations with the simple use of switches that can be controlled by a computer or controller on which are loaded switch command programs, and programs that implement algorithms, known per se, to search for operating conditions. optimal, in which the function to be optimized can be both technical and economic.

It is observed that the more numerous the elements of both FER and SAE, the more refined are the searches for optimal coupling between the various elements.

Ultimately, it is now clear how a RES can also be connected to an SAE, as well as to an inverter, without going through DC-AC and AC-DC conversion stages, simply by appropriately configuring the series-parallel configurations of RES and of SAE in order to make the output voltage of the RES and the optimal input voltage for the SAE charge as close as possible. As for the currents, the problem appears less critical as the SAE can generally accept a wider range of currents, generally it is essential that there is the minimum current capable of triggering the charging process, while currents that are too high could overheating the battery too much, compromising its performance and, in extreme cases, damaging it. In the case of very low productions, and therefore of low currents, it is possible to foresee the charge of a few modules of the SAE, at the limit only one module at a time, and therefore it is possible to foresee the operation of the coupling even with a very low current. if you think that normally SAEs can be very granular systems composed of tens or hundreds of elementary modules.

Normally SAEs are of the electrochemical type, whether they are classic lead or gel batteries, whether they are electrolyte circulation systems, or other accumulation systems of various types.

In any case, it is possible to exploit the fact that SAEs are made up of a certain number of elementary modules or cells that are connected in series and in parallel to appear as a system with only one pair of input / output terminals. By connecting various modules to each other in series, a circuit is obtained that has a higher voltage at the terminals, and then by connecting the series-circuits together in parallel, a circuit is obtained that is capable of absorbing / delivering ever greater currents as the number of circuits connected in parallel.

The possibility of operating an appropriate set of switches with absolute flexibility also allows you to work using only portions of the SAE. This is very useful especially when very low energies are in play, being charged.

Therefore, all the flexible connection diagrams of the various RES modules previously illustrated can also be applied to the elements of the SAE storage systems. An example of realization of interconnections between SAE modules will be described below.

In the coupling between FER and SAE, being able to act both in the control of the input voltage to the SAE and in the control of the output voltage from the FER, it is generally possible to find the combinations that are closest to the optimal solution.

Also for SAEs as for RES, in addition to the possibility of flexibly combining the series / parallel connections, it is also important to be able to realize the sectionability. For example, in the case of particularly low energy production values to be stored, it is possible to physically charge only some elements of the SAE, or, since the different elements of the SAE have a different state of charge, it is possible to proceed to discharge phases or of selective charge.

The present invention allows to realize a further functionality that can be performed locally within a â € œSmart Gridâ €. This functionality is independent of the hardware choices that affect the computers responsible for operating the â € œSmart Gridâ €, and requires that the DC adaptation problems of the various parts of the systems be solved (FER - SAE - inverter), and moreover that the distribution of available energy (from RES or SAE) is optimized.

The present invention therefore solves both problems of continuous adaptation between the various parts of the system, and problems of managing the energy resource by means of a controller, which can be a dedicated device or a function performed by one of the various computers certainly present in the â € œSmart He shouted.

Figure 6 illustrates the main elements of the system, which includes at least one RES, at least one SAE, and at least one CNT controller. RES and SAE are located upstream of the DC / AC conversion systems including at least one INV1 inverter system towards external loads, such as the public electricity distribution network, and / or at least one INV2 inverter system towards local internal loads, such as the home electrical network.

The example of figure 6 shows two load nets because this is the most typical case, as it is useful to distinguish between private loads, which can be managed with â € œSmart Gridsâ € criteria, and associated in a way privileged to RES, for example for self-consumption, and external generic loads connected to an external or public network. In fact, any number of cargo nets may be present.

The dotted lines indicate exchanges of information and / or commands, while the solid lines represent flows of electrical energy. In particular, there is a bidirectional exchange of information and / or commands between the CNT controller and FER, SAE, INV2 (for example relating to forecasts of electricity availability, or diagnostics), while the CNT controller can generally only receive information from the external network. through the INV1 inverter (for example, it can receive information on the price at which the grid is willing to acquire or sell any available energy). RES can supply energy flows to SAE, and to inverters INV1, INV2.

SAE can receive energy to be stored from RES and can supply energy to inverters INV1, INV2.

Obviously, nothing prevents the public network from receiving commands and information from the CNT controller. Furthermore, it is also possible to manage an energy flow from the external grid to SAE: this option could be useful for purchasing energy at a favorable price, in appropriate time intervals, to be used for example during peak hours in which the price of the energy would be maximum and in which it is not expected to produce enough energy by RES.

It is also possible to configure SAE so that it can supply different voltage values to pre-established outputs, possibly reconfigurable by the controller, which can therefore be used by local loads operating at direct voltage and / or by DC / DC converters that adapt the voltage levels that can be generated. from the SAE for these loads. In this way, efficiency is gained by eliminating or at least decreasing the energy dissipation due to the DC / AC conversion carried out by the inverters and the subsequent one carried out by the power supplies of the devices operating continuously (for example mobile phones, notebooks, battery chargers, etc.) .

The exchange of information between the CNT controller and the INV1, INV2 inverter can take place on an ethernet bus while the exchange of information between the controller and the RES and between the controller and SAE can take place on â € œ Conveied Wavesâ €. It is possible that SAEs of a certain size are already equipped with their own controller that performs some system management functions; in this case also the communications between the CNT controller and the SAE controller can take place on an ethernet bus, while the control information of the switches between the SAE controller and the switches themselves can transit on "Conveyed Waves".

The RES can also be associated with a specific controller that communicates with the CNT controller on an ethernet bus, and then transmits the commands to the switches of the RES itself on â € œDirected Wavesâ €.

The controllers of the SAE and of the FER can be seen as extensions of the CNT controller, therefore in the following we will always refer to the communications between the controller and the SAE and between the controller and the FER, meaning by the controller the CNT controller.

When we refer to communications on ethernet bus, we mean that the communication is between computers and that therefore a common technique can be used to manage this type of communication: for example, even a WiFi communication or an M2M technique.

A typical example of using a network such as the one described with reference to Figure 6 is now considered.

The production of a RES is considered given by a modular direct current electricity generation plant consisting of N panels in a generic instant T1. At this instant T1 the RES is making available an amount of power Pf1, while the network of internal loads is requesting a power Pc1, with Pc1 <Pf1.

The CNT controller is connected to the INV1 network inverter and to the INV2 local inverter, and can exchange information with them. The simplest case is that you exchange information on an ethernet bus.

Furthermore, the CNT controller is connected to all the pairs of I / O terminals of the FER and also of the SAE. On these terminals it can carry out direct current and voltage measurements, and can transmit the commands necessary for the configuration of both the RES and SAE by means of “Convogliate Waves”. In the hypothesized case (Pf1> Pc1) the controller, according to a possible operating mode, distributes a part of Pf1 equal to the requirement Pc1 on the output connected to the INV2 inverter. In addition to this, the controller combines the parallel series connections of the RES so that on the output connected to the INV2 inverter there is a current-voltage profile that optimizes the performance of the conversion elements.

The remaining power made available by the RES (Pf1-Pc1) is instead made available entirely on the output connected to the SAE. In this case, the CNT controller will be responsible for configuring both the SAE and the FER modules in such a way that the SAE can work with maximum storage efficiency. For example, if the excess power is low, it might be convenient to activate only a part of the battery modules on the SAE charge input, consequently it will be necessary to configure the part of the RES modules that produce energy as well. in excess in order to achieve, in the FER-SAE connection, the appropriate current-voltage characteristic to optimize the storage efficiency.

In the event that the storage system is already at the maximum state of charge, the excess power can be made available on the RES output connected to the external grid through the INV1 inverter. A choice of this type can also be made if, for example, the external grid requires energy. Therefore the CNT controller, also on the basis of the information available on the internal needs and on the request of the grid, may decide to transfer the excess energy produced to the public grid rather than accumulate it.

At this point it is clear how the CNT controller can be very useful in the case of diffusion of â € œSmart Gridâ €. In fact, that controller is in possession of all the information necessary to optimize at the same time both the allocations and the adaptations necessary for the exchanges of energy between RES, SAE and loads of different nature.

Not only are the quantities of energy exchanged in the various directions managed in an optimal way, but also all the current-voltage adaptations are managed without resorting to unnecessary AC-DC and DC-AC conversion equipment. In fact, all these adaptations can be made through the operation of circuit-breakers and therefore reducing losses and inefficiencies due to conversions.

The typical case that the known art today tries to manage by introducing flexible configuration techniques is the case of production derived from photovoltaic systems in which some panels can be occasionally shaded, and therefore their production can drastically decrease compared to other panels. not shaded. As has already been said, this case is normally managed by excluding all the string in which these panels are inserted, thus entailing in any case a waste of energy.

It is already known in the art to equip the panels with sensors that detect anomalous conditions, such as shading or damage. Then, in accordance with the present invention, the CNT controller can detect these anomalies simply with measurements at the terminals of the panels, and reconfigure the RES in a flexible way by isolating only the panels involved and not the complete strings.

In the following, more detailed examples of the system object of the invention are described.

Figure 7 represents a greater detail of an example of embodiment of the system of Figure 6.

The SAE storage system can be coupled directly to DC loads DLC1 by means of an appropriate DC / DC1 converter, and / or indirectly to the same or other DC loads DLC2 by means of another DC / DC2 converter. Indirect coupling takes place via a CFE1 energy flow switch, which receives energy from RES and SAE at the inputs, and which, suitably controlled by CNT, supplies electricity to the inverters INV1, INV2 (fig. 6), and / or towards said DC / DC2 converter. The INV1, INV2 inverters can also be made by means of an INV inverter system (fig. 7), followed by a switch for the flow of electricity to local AC loads ACL, and / or to the public network PN from which it can also be introduced. electricity, as described above.

The CNT controller receives information on the status of the RES and SAE directly or through the switching control units as well as on the conditions of supplying the current voltage of the RES. More specifically, it has already been said above that the FER component panels are equipped with sensors for the operating conditions and voltage and current supply: these data are supplied to a CIV module which, appropriately controlled by CNT, can determine the conditions of RES configuration through a CFER control unit also directly controlled by CNT.

Depending on the needs, the energy coming from the RES, through the CIV module, is conveyed by the CFE1 controller to the INV inverter, and / or to the SAE, and / or directly to the DCL2 load.

The CNT controller also receives information on the status of the component energy storage modules of SAE through the CSAE control unit to which the sensors of the operating conditions of the SAE modules are connected. This information is also used by CNT to determine the optimal SAE configuration.

With reference to figure 8, a possible configuration of SAE is highlighted which includes a determined number of storage units or cells (normally BAT batteries), organized in branches or strings R1, R2, R3. Each cell comprises a charge sensor C and switches, controlled by the CSAE module, which can connect the various cells in series to others of the relative branch to which they belong, or they can exclude them. Other switches, controlled by the CSAE module, can connect the various branches in series or parallel or exclude them. The charge sensors C provide the relative indications on the state of the cells to the CSAE module.

Depending on the voltage and current available at the moment, one or more cells of the SAE can be charged.

Each branch of the SAE has a current sensor SC connected to an RC current regulator, in turn connected in a bidirectional way to the CFE1 energy flow switch, allowing to control the current and, for example, to impose that it does not exceed a certain default value to avoid damaging the branch cells during charging. Even with the configuration shown in the figure it is possible to simultaneously load some strings of cells and drain energy from others, if these were charged to power a local DC load or even an AC load passing through the inverter, giving great flexibility of Use at the plant.

In this way, the probability that the system supplies energy to users is greatly increased, even in the partial or total absence of sunlight, greatly reducing dependence on the electricity distribution network. The control units of the RES and SAE switches can also be integrated in the latter or in the controller. Even more strings can be loaded or used in parallel in case of production or consumption of currents higher than those that can be absorbed or generated by a single string.

The decision-making process of the CNT controller regarding the operating status of the system is illustrated with reference to the flow diagram of figure 9. The controller acquires from the CIV unit the state of energy generation by FER (block 91). If the INV inverter cannot be activated (block 92), all the drained energy is transferred from the RES to the SAE (block 96). Otherwise, it occurs if the grid is able to absorb the energy generated by the RES and / or if it is convenient to transfer it at the moment as it has a favorable selling price, and / or the local loads do not need it and / or the battery is fully charged (block 93). If the verification gives a positive result (block 94) the transfer of the RES energy to the grid is activated (block 95) otherwise it converges on the SAE (block 96).

The flow chart of Figure 9 can be implemented in various forms, all equivalent. It can be carried out by cyclic repetition of a group of instructions, by means of interrupt mechanisms coming from decentralized control units that verify the decision-making conditions, by polling mechanisms (periodic interrogation) of peripheral devices by the controller, and so on. It can be implemented automatically, partially or totally programmable for example by timer, and / or even manually by means of commands entered by a human operator.

The CNT controller is able to check the state of energy generation by the RES, the absorbing capacity of the network, the charging capacity of the SAE modules, the actual or estimated current consumption of the local loads, and also decide on the basis of parameters programmed by the operator (maximization of profits, maximum continuity of power supply of local loads, maximization of the state of charge of the battery, etc…) which energy transfer policy to implement.

In the case of generic heterogeneity of the modules, it is necessary for the controller to know, module by module, the instantaneous production. This can be guaranteed, for example, by equipping each RES module with a device that measures production data and communicates them to the controller, through sensors already available on the market, and for example installed on the modules themselves.

However, it is also possible for the controller to carry out measurements autonomously, without inserting sensors on the modules, for example by carrying out measurements on the pairs of anode and cathode terminals of the modules, appropriately controlling the switches on each module. In fact, the controller can execute programs which, starting from the available measurements and the knowledge of the system (module specifications, number of modules, their type, orientation, expected returns, etc.), carry out estimates and evaluations that make it possible to apply search algorithms for optimal module connection configurations, and possibly also command the exclusion of some of them, for the various reasons described above.

The control system of the present invention can be advantageously implemented by means of a computer program which comprises coding means for carrying out one or more steps of the method, when this program is executed on a computer. Therefore, it is intended that the protection scope extends to said computer program and further to computer readable means comprising a recorded message, said computer readable means comprising program coding means for carrying out one or more steps of the method, when said program is run on a computer.

Implementation variations to the described non-limiting examples are possible, without however departing from the scope of protection of the present invention, including all the equivalent embodiments for a person skilled in the art.

The advantages deriving from the application of the present invention have already been described above.

Ultimately, the system therefore solves numerous problems related to the integration of â € œislandsâ € or â € œenergy districtsâ € of various sizes in which RES, SAE and local loads are present, optimizing the couplings and methods of distributing energy flows. All with the addition of a few simple switches which, among other things, can be integrated into the existing modules of both the RES and SAEs, allowing the controller to manage and solve all the problems of coupling and partitioning of the productions, avoiding unnecessary DC / transformations. AC and AC / DC, optimizing SAE and RES yields. In fact, the management part is entrusted to the controllers who would in any case be expected to govern the â € œenergy districtâ € or â € œislandâ €, as envisaged by the evolution of the electricity grids according to â € œSmart Gridâ € concepts.

From the above description the person skilled in the art is able to realize the object of the invention without introducing further construction details.

Claims (9)

CLAIMS 1. System for the generation and use (for storage and supply) of electricity produced from modular direct current electricity sources, comprising: - a system of interconnected modules for the production of electricity in direct current, said system of interconnected modules being positioned upstream of one or more DC / AC conversion systems; - a system of interconnected elements for the accumulation and supply of electrical energy produced by said electrical energy production modules, said system of interconnected elements being positioned upstream of said one or more DC / AC conversion systems; - at least one electronic control unit, capable of configuring in a variable way the interconnections between said modules and the interconnections between said elements in such a way that at least some of said interconnected modules can supply electricity directly to at least some of said elements for storage and supply, and / or to said one or more DC / AC conversion systems, and that at least some of said elements can deliver electricity directly to said one or more DC / AC conversion systems. 2. System as in claim 1, in which said at least one electronic control unit is also configured in such a way that said system of interconnected elements supplies electricity directly to systems for using DC electricity, possibly by means of DC conversion /A.D. 3. System as in any one of the preceding claims, wherein said at least one electronic control unit is configured so as to determine voltage and current at the outputs of said system of interconnected modules and at the outputs and inputs of said system of elements interconnected, determining the series and / or parallel interconnection configurations of said modules and elements. 4. System as in any one of the preceding claims, wherein said system of interconnected modules for the production of electrical energy comprises: - two or more of said modules, each module being equipped with an anode clamp and a cathode clamp; - at least one first electrical line connected to an anode terminal and a cathode terminal of the system; - first electrical switch means, at least one at each of said modules, said first electrical switch means being configured so as to connect said anode and / or cathode terminals of a module with anode and / or cathode terminals of another module, or to said first electrical line, or to exclude one or more modules from the system, based on commands from called at least one electronic control unit. 5. System as in claim 4, wherein said system of interconnected modules for the production of electric energy comprises two or more first strings, each string comprising one of said first electric lines, said at least one electronic control unit comprising means for determining parallel connections between said first strings, or to split groups of first strings in parallel. 6. System as in any one of the preceding claims, wherein said system of interconnected elements for the accumulation and supply of electrical energy comprises: - two or more of said elements, each element being equipped with an anode clamp and a cathode clamp; - at least a second electrical line connected to an anode terminal and a cathode terminal of the system; - second electrical switch means, at least one at each of said elements, said second electrical switch means being configured so as to connect said anode and / or cathode terminals of one element with anode and / or cathode terminals of another element, or to said second electric line, or able to exclude one or more elements from the system, on the basis of commands coming from said at least one electronic control unit. 7. System as in claim 6, wherein said system of interconnected elements for the accumulation and supply of electric energy comprises two or more second strings, each second string comprising one of said second electric lines, called at least one unit of electronic control comprising means for determining parallel connections between said second strings, or for splitting groups of second strings in parallel. 8. Method for managing said system as in any one of claims 1 to 7, comprising the steps of: - interconnection of each of said modules for the production of electrical energy with other modules, and / or exclusion of one or more of said modules, by activating said first switch means, by means of said at least one electronic control unit; - interconnection of each of said elements for the accumulation and supply of electrical energy with other elements, and / or exclusion of one or more of said elements, by activating said second switch means, by means of said at least one unit electronic control. 9. Method for managing said system as in claim 8, comprising the step of interconnecting said first and / or second strings in parallel and / or sectioning groups of said first and / or second strings, by activating said first and / or second switch means on said at least one first and / or second electrical line, by means of said at least one electronic control unit.